[1] Univ Montreal, Ctr Hosp, Montreal, PQ, Canada
[2] Univ Washington, Sch Publ Hlth, Fred Hutchinson Canc Res Ctr, Seattle, WA 98195 USA
[3] Univ Washington, Sch Publ Hlth, Dept Epidermiol, Seattle, WA 98195 USA
[4] Brigham & Womens Hosp, Boston, MA 02115 USA
[5] Harvard Univ, Sch Med, Boston, MA USA